For many years attention has been directed to the development and manufacture of systems for cleaning swimming pools. Thus, for public swimming pools and for most of the larger private swimming pools, particularly of below ground construction, a built-in water recirculation system is provided for filtering the water. Such recirculation systems usually include a water surface skimmer which is in communication with a suction pump at the filter station. The suction pump draws off water from the pool through the skimmer, draws the water through the filter station, and returns filtered water to the pool through a pressurized outlet. While the water is out of the pool it can also be heated.
Surface skimmers typically have an opening or inlet channel at the pool water level. The suction pump, through its water recirculation action, draws surface debris into a perforated basket within the well of the skimmer. Surface skimmer systems, in and of themselves, cannot remove debris which has settled to the bottom of the pool. Thus, pool owners and pool maintenance operators in the past have had to vacuum the bottom of the pool with an underwater suction cleaner directly connected by a flexible hose to the filter and pump station associated with the pool. In recent years skimmer systems have also included a cover plate for the skimmer well which includes means to interconnect the system to an underwater suction-operated pool cleaner and means which allows the system to alternately provide water surface debris skimming action and underwater pool cleaning action.
Underwater suction-operated pool cleaners, connected by suction hose means to the skimmer as a water suction source, operate by the suction of water drawn through the device thereby powering an internal turbine which enables the device to move about the pool floor while vacuuming the pool floor by the suction action of the cleaner. Debris that has settled to the pool floor is sucked into the device and passed out through the suction hose. In the past, underwater suction-operated pool cleaning devices, utilizing the skimmer system as the suction source, required an upstream debris collector or trap installed for catching the floor bottom debris carried by the hose before it reached the skimmer. This was necessitated because the suction hose of the underwater device had to be alternately connected to and unconnected from the suction inlet at the bottom of the skimmer well for operation of the device with removal of the debris basket otherwise required in the well for normal skimmer action.
Although underwater suction-operated pool cleaners have provided a very effective means for cleaning the floor of swimming pools and even the walls thereof, as indicated above, initial use of such cleaners via suction connection through pool skimmers necessitated manual hose connection directly to the suction inlet at the bottom of the skimmer well below the debris basket. Thus, the skimmer had to be inactivated while the cleaner was in operation with the result that during floor cleaning of the pool floating debris at the pool surface was not collected.
In most swimming pool operations the skimmer is not operated in a continuous fashion, i.e., the suction pump at the external filter-pump station draws water through the skimmer on a time controlled basis. Thus, most pool filtration systems operate on timers which cycle suction pump operation between "on" and "off" periods that may last for between 10 and 20 minutes during the twenty-four hour day. Further, underwater suction-operated pool floor cleaners are not operated on a continuous basis with pool floor cleaning being conducted over "on" and "off" cycle periods that also may last 2 to 8 or more hours.
To overcome the requirement that the pool owner or pool maintenance operator alternate the path of suction water between the pool skimmer and an underwater pool cleaner via the suction pump, there has been disclosed in U.S. Pat. No. 4,643,217, granted to H. E. Frentzel, an indexable valve which fits into the suction inlet of the skimmer. Such valve receives the suction hose connected to the underwater pool cleaner. In a first operating position the valve allows water to be drawn through the suction hose of the cleaner directly into the suction inlet of the skimmer. In its second operating position, water is passed through the valve directly from the skimmer. The valve of the Frentzel patented device indexes through an intermediate position whenever the suction pump is inactivated.
Frentzel, in his subsequent U.S. Pat. No. 4,776,953, indicated that the foregoing described indexable valve operated quite well with existing time controlled suction pump and filter systems. Thus, the indexable valve was designed such that every time the filtration system is turned off, the valve would shift through its intermediary position, to one of either the first or second positions. In this manner, the pool would alternately be skimmed or vacuumed automatically, throughout the day, without any intervention from the pool owner or maintenance operator. The earlier Frentzel patented system required an intermediary debris trap mounted upstream from the suction inlet of the skimmer to collect the debris before it passes into the skimmer. Frentzel found that the upstream debris trap was not desirable since such traps are difficult to clean and the pool owners and maintenance operators were accustomed to servicing a standard skimmer debris basket.
In his U.S. Pat. No. 4,776,953 Frentzel proposed that a cover plate be installed across the top of the skimmer well to seal off the upper surface of the well. Pipe means was provided in the skimmer to connect the suction hose from the underwater pool cleaner to an orifice in the plate so that water and debris from the pool cleaner could be suction through the well and its enclosed debris basket. The skimmer cover plate further included an automatic indexable valve positioned over a second orifice in the plate and movable between two primary positions. In a first primary position, the water flow is restricted through the valve so that the suction generated in the well by the suction pump is diverted to draw water through the cleaner hose connected to the underwater pool cleaner. When the valve is in its second primary position, surface water and debris are drawn directly through the valve and into the skimmer well. In both primary valve operating positions, water passing through either the cleaner hose or the valve is strained through the debris basket within the well. The Frentzel valve not only indexes (reciprocates) between upper and lower primary positions, its central piston rotationally indexes whereby the valve is caused to reciprocate to an intermediate position whereby water and debris is drawn into the skimmer well and debris basket through the skimmer as-well-as from the underwater pool cleaner.
As described above, the second Frentzel patent discloses an improved pool water cleaning system, with respect to prior art systems, which includes an indexable valve for alternately directing suction water either drawn through an underwater pool cleaner hose or drawn through the channel leading from the pool to the skimmer well and through the debris basket therein. However, the Frentzel indexable valve is complex in structure and has encountered problems in operation. For example, the central piston and its conically shaped sealing element which in its lowest position seals off the skimmer plate valve orifice (leading from the upper water inlet section of the skimmer to the skimmer well) is supported and reciprocates on a central rod which is threaded to a support member located below the valve orifice, The support member includes a number of struts that are in the flow path of the surface water and leaves that are drawn into the debris basket by the suction pump with the leaves and other pool debris frequently hanging up on such struts and impeding flow into the basket. Further, the central piston and sealing element are biased upwardly by a spring surrounds the central support rod. Because the valve's central piston indexes (reciprocates) upwardly and downwardly and rotates (in indexing fashion) during operation of the valve, the spring frequently becomes twisted and resists further rotation of the central piston thereby requiring replacement.
Accordingly, it is a principal object of the present invention to provide a new and improved flow shift valve which may be used in conjunction with a pool skimmer and an underwater pool cleaner.
It is another object of the invention to provide a new and improved flow shift valve system which allows an underwater suction-operated pool cleaner to be operated in conjunction with swimming pool surface water skimmer systems of common design and operation.
It is still a further object of the invention to provide a skimmer cover plate which is mountable to the top of a pool skimmer well and which includes thereon an improved flow shift valve of unique construction for directing the alternate operation between an underwater suction-operated pool cleaner and the pool skimmer system.
Other objects and advantages of the invention will be apparent from the following summary and detailed descriptions of the unique flow shift valve of the invention taken together with the accompanying drawing figures.